Apparently, folks are regularly making these motors by hand, they are quite simple.

Interestingly, they are synchronous, but their magnetic field rotates much faster than the rotor does. In the examples on the link above, the field rotates at seven times the speed of the rotor.

Usually they are used as BLDC motors (== trapezoidal drive) but this probably produces too much torque ripple for a turntable application. However I see no reason why they could not use sinusoidal drive like any 3 phase motor.

There's probably another name for these motors, and I imagine, some motor company sells them, but I haven't been successful finding any, so far, apart from hobbyist versions.

Mark Kelly

17th June 2007 03:30 AM

Re: LRK motor for Turntable?

Quote:

Originally posted by pixpop

Usually they are used as BLDC motors (== trapezoidal drive) but this probably produces too much torque ripple for a turntable application. However I see no reason why they could not use sinusoidal drive like any 3 phase motor.

As I understand it the separated phase is an integral part of the design so it cannot be driven by a sinusoidal wave.

Quote:

There's probably another name for these motors

Yes they are known as separated phase sector (SPS) motors.
Information is pretty scant.
The info on the LRK site lacks the important part of the original paper (the derivations of the equations). Does anyone out there have the original with the equations?